pandas とは？

Pythonで始めるデータサイエンス入門

Hillary Green-Lerman

Lead Data Scientist, Looker

pandas でできること

さまざまなソースから表形式データを読み込み
特定の行・列を検索
集計統計量を計算
複数ソースのデータを結合

pandas での表形式データ

表形式データ

+-------------------------------------------------+
|        suspect        |     location    | price |
+-----------------------+-----------------+-------+
| Fred Frequentist      | Petroleum Plaza | 24.95 |
| Ronald Aylmer Fisher  | Clothing Club   | 20.15 |
+-------------------------------------------------+

DataFrame

                suspect        location  price
0      Fred Frequentist  Perolium Plaza  24.95
1  Ronald Aylmer Fisher   Clothing Club  20.15

CSV ファイル

CSV の読み込み

import pandas as pd

df = pd.read_csv('ransom.csv')

DataFrame の表示

df = pd.read_csv('filename.csv')

print(df)

                 suspect         location          item  price
0         Kirstine Smith  Petroleum Plaza           gas  24.95
1       Fred Frequentist      Burger Mart         fries   1.95
2           Gertrude Cox      Burger Mart         fries   1.95
3   Ronald Aylmer Fisher    Clothing Club         shirt  14.25
4         Kirstine Smith    Clothing Club         dress  20.15
5       Fred Frequentist   Groceries R Us     cucumbers   2.05
6         Kirstine Smith    Clothing Club         dress  20.15
7           Gertrude Cox  Petroleum Plaza   fizzy drink   1.90
8           Gertrude Cox      Burger Mart         fries   1.95
9   Ronald Aylmer Fisher    Clothing Club         shirt  14.25
10  Ronald Aylmer Fisher  Petroleum Plaza       carwash  13.25
11  Ronald Aylmer Fisher    Clothing Club         shirt  14.25
12        Kirstine Smith  Petroleum Plaza           gas  24.95
13      Fred Frequentist   Groceries R Us          eggs   6.50
14          Gertrude Cox  Petroleum Plaza           gas  24.95
15      Fred Frequentist   Groceries R Us          eggs   6.50
16  Ronald Aylmer Fisher   Groceries R Us          eggs   6.50
17      Fred Frequentist   Groceries R Us        cheese   5.00

DataFrame の確認

df.head()

print(df.head())

                 suspect         location          item  price
0         Kirstine Smith  Petroleum Plaza           gas  24.95
1       Fred Frequentist      Burger Mart         fries   1.95
2           Gertrude Cox      Burger Mart         fries   1.95
3   Ronald Aylmer Fisher    Clothing Club         shirt  14.25
4         Kirstine Smith    Clothing Club         dress  20.15

DataFrame の確認

df.info()

print(df.info())

<class 'pandas.core.frame.DataFrame'>
RangeIndex: 26 entries, 0 to 25
Data columns (total 3 columns):
 #   Column        Non-Null Count  Dtype  
 --  ------        --------------  -----  
 0   letter_index  26 non-null     int64 
 1   letter        26 non-null     object 
 2   frequency     26 non-null     float64 
dtypes: float64(1), int64(1), object(1)
memory usage: 704.0+ bytes

DataFrame の確認

練習しましょう！

Pythonで始めるデータサイエンス入門